Required Navigation Performance (RNP) is a type of performance-based navigation that allows an aircraft to fly a specific path between two three-dimensionally defined points in space. For example, each phase of flight may be assigned a virtual tunnel (may be referred to as “tunnel/highway in the sky”) through which the aircraft is required to traverse through. The dimension of a particular tunnel is established by the RNP of that particular phase of flight. The RNP may further establish the level of performance required for that phase of flight. For instance, an RNP of 10 means that an aircraft navigation system must be able to calculate its position to within a circle with a radius of 10 nautical miles. An RNP of 0.3 means the aircraft navigation system must be able to calculate its position to within a circle with a radius of three-tenths of a nautical mile.
Such a performance-based navigation may further require on-board navigation performance monitoring and/or alerting. That is, the aircraft navigation system (or the flight management system in general) may be configured to determine an Actual Navigation Performance (ANP). ANP is the flight management system's estimate of the quality of its position determination, or its current performance. The lower the ANP, the more confident the flight management system is of its position estimate.
A pilot may be required to mentally process various types of information when flying through a tunnel in the sky. Such information may include the containment limits of the RNP, the current position of the aircraft, the ANP of the aircraft and the like. Furthermore, because such information may be provided by different devices/instruments, the pilot may be required to continuously read data from different devices/instruments. Therein lies the need to provide an integrated graphical representation of the performance attributes for performance-based navigation operations.